Heating and ventilating apparatus



Aug. 24, 1943. G. E. OTIS HEATING AND VE NTILATING APPARATUS 2 Sheets-Sheet 1 Filed Dec.

11:1 Gem/o E. Of/s G. E. OTIS 2,327,663 HEATING AND, VENTILATING APPARATUS Fil ed Dec. 6, 1940 2 Sheets-Sheet 2 T I l v/L En 8 q! (II a Gerald E. 07/5 Patented Aug. 24, 1943 HEATING AND- VENTILATIN G APPARATUS Gerald E. Otis, Moline, Ill., assignor to The Herman Nelson Corporation, Moline, 111., a corporation of Illinois Application December 6, 1940, Serial No. 368,763

13 Claims.

This invention relates in general to heating and ventilating apparatus, and is more particularly concerned with apparatus of the class commonly designated as unit ventilators.

It is a primary object of the hereindescribed invention to provide in a unit ventilator adapted to circulate a mixture of fresh and recirculated air, means whereby, under conditions when the outdoor air is liable to be much colder than the indoor air, the cold air admixture will be tempered before the mixture is effected, so as to produce a better mixture and avert the danger of cold air escaping into the room through the recirculation inlet. -In short, the present invention seeks to prevent what is frequently referred to as blow-through. Heretofore. this has been a frequent source of trouble with apparatus of this kind, especially in windy weather, when cold air puffs out of the recirculation inletand spreads over the floor of the room in which the ventilator is placed and causes disagreeable drafts.

A further object is to provide an auxiliary fresh air supply which will assure a certain limited amount of fresh air for ventilation whenever the radiatoris filled with steam and the ventilator is in operation, and which will be closed against the admission of fresh air whenever the radiator is not warm or the fans are not running.

Another object is to provide improved apparatus of the hereindescribed type and including an improved radiator structure that will insure better graduated control of the temperature of the heated air and eliminate cold spots occasioned by air-binding in the radiator.

A still further object is to provide improved control means for unit ventilators.

Other objects and features of the invention will more fully appear from the following detailed description taken in connection with the accompanying drawings, which illustrate a preferred embodiment thereof, and in which:

Figure 1 is a. vertical sectional view' taken through a unit ventilator embodying the features of the present invention;

Figure 2 is a plan view partly in section of a radiator for the unit ventilator; I

Figure 3 is a view schematically illustrating an electrical control scheme for the unit ventilator; and I Figure 4 is a similar view illustrating an alternate pneumatic control scheme 'for the unit ventilator.

As shown on the drawings:

Referring to Figure 1, a unit ventilator embo dying the features of the present invention, as generally indicated at I, is represented in its in stalled position for serving a room or space 2. The unit consists of a cabinet or housing 3 through which air is circulated and conditioned, this housing being arranged to enclose the required air passages and operatingparts of the unit. The form of ventilator illustrated and described is adapted to set on the floor, against a wall of the room served. In the commercial types, the height of the ventilator is usually such as will allow it to be placed under a window and the length is usually about once to twice the height. As is well known in the art, the size, shape and detailed construction of the cabinet are more or less optional or discretionary and the unit location is largely a matter of choice, influenced by service considerations and the availability of a suitable source of fresh air.

The cabinet 3 is provided with a radiator 4 arranged to subdivide the cabinet into two major portions. One of these portions constitutes a relatively large space 5 above the radiator, this space being adapted to contain a motor driven fan or power unit 6 adjacent the top of the cabinet. This space may accordingly bedesignated as the fan compartment. It serves as a suction compartment for the fan which discharges through an outlet grille 'l in the top of the cabinet.

The radiator 4 preferably consists of two sections or subdivisions 4--a and 4-1). A partition 8 separates these two radiatorsections and extends to the. bottom of the cabinet, thus subdi viding the other major portion below the radiator into a fresh air compartment 9 and a recirculated air compartment I0. I

A recirculation inlet II in the lower front of the cabinet affords communication between the room 2 and the recirculated air compartment l0. Openings l2 and I3 in the rear of the cabinet register with a duct [4 through the wall against which the cabinet sets, this duct serving to establish communication with a source of fresh air. The wall duct l4 is preferably protected by a screened louver l5. The opening I2 constitutes a, main fresh air intake into the fan compartment 5, while the opening I3 is an auxiliary radiator section 4-a while communication between the recirculated air compartment I and the fan compartment 5 is afforded through the fresh air passages of the radiator section 4-1;. In the latter case, the flow of air through the radiator is controlled by recirculation dampers I8. Hence, fresh air may flow directly into the fan compartment 5' when the main fresh air damper I6 is open, and indirectly into the fan compartment through the fresh air compartment 9 and the radiator section 4*, when the auxiliary fresh air damper is open. Recirculated air may flow indirectly into the fan compartment through the recirculated air compartment l0 and the radiator section 4-b, when the recirculation dampers l8 are open.

A link l9, pivotally connected to lugs on each of the dampers I8, causes these dampers to operate in unison, as a set. A second link 2|, pivotally connected to the ink l9 and to a lug 22 on the damper l6 coordinates the movements of the dampers l6 and I8. The arrangement is such that, when the main fresh air damper I6 is closed, the recirculation dampers l8 will be opened to a predetermined maximum degree; so that as the main fresh air damper is progressively opened the recirculation dampers will progressively move toward a closed position until, when the main fresh air damper is fully opened, the recirculation dampers will be fully closed;

and, so that as the main fresh air damper is progressively moved from the open to the closed position, the recirculation dampers will be moved progressively from a closed to an open position.

The main fresh air damper It may be adjusted to a closed, open or intermediate position, with inversely corresponding adjustment of the recirculation dampers l3, by means of a link 25 pivotally connected to a damper crank 26 and to an arm 21 of a pneumatic damper motor 28. This damper motor is arranged to be controlled by a thermostat 23 in response to varying room temperatures within a selected range, as shown in Figures 3 and 4. For example, the thermostat 29 may be so set that when the room temperature is 72 degrees or less, the main fresh air damper l6 will be closed and'the recirculation dampers l8 open to maximum; when the room temperature is 74 degrees or more, the main fresh air damper will be fully opened and the recirculation dampers fully closed; and when the room temperature is at any point between 72 degrees and 74 degrees, a mixture of air from the two sources will be obtained in which the relative proportions will depend on the precise room temperature. The proportion of fresh air is increased as the room temperature approaches 74 degrees and is decreased as the room temperature approaches'72 degrees.

The auxiliary fresh air damper I1 is shown as being arranged for operation by a link 30 which is pivotally connected to a damper crank 3| and to an arm 32 of a damper motor 33.

The damper motor 33 may be of a type well known in the art and sometimes referred to as a heat motor. As shown in Figures 3, when the motor is placed in an electrical circuit 34 a spring 35 in the motor holds the motor arm 32 in a position to keep the damper I! closed so long as the circuit is open, but when the circuit is closed the electrical current vaporizes a'volatile fluid in the motor, thus creasing a pressure which acts on the head of a bellows to counteract the spring tension and move the arm 32 so as to open the damper. The electrical circuit 34 is taken from a supply circuit 33 which supplies current to the fan motor 3 through a control switch 31, the circuit 34 being connected between the switch and'fan motor and opened and closed by a thermostat 38. This thermostat may be of either the contact or insertion type, placed so as to respond to the temperature of the radiator section 4- a. Hence, whenever the fan 6 is running and the radiator section is warm, the auxiliary fresh air damper I! will be open but when the heat is cut off the radiator section 4-12 or the fan is not running, the damper I! will be closed.

The damper motor 33 and the thermostat 38 may also be of the pneumatic type, as indicated in Figure 4, in which event a branch compressed air line 39 to the damper motor 33a would be controlled by an electric-pneumatic valve 40 operated by an electrical circuit 4| so as to render the damper motor inoperative when the current is cut off from the fan motor. The damper l'l would, of course, be closed whenever the air pressure in the branch line 39 were cut ofl in any way.

The supply of steam to the radiator 4 is controlled by a valve 42 which is operated by a motor 43 controlled by the room thermostat 29. The control may be such that, within a selected room temperature range, the valve will be fully opened when the room temperature is at or below the low limit of the range, and closed when the room temperature reaches or exceeds the upper limit of the range, and so that the valve will assume a proportionately intermediate position when the room temperature is at any point between the range limits.

Let it be supposed, for example, that the radiator valve 42 is thus controlled within a range of from 70 degrees to 72 degrees while the dampers l3 and I8 are controlled as hereinbefore explained within a range of from '72 to 74 degrees. Assuming that the system is shut down over the night period; then, before it is started up in the morning both of the fresh air dampers l6 and I! will be closed, whereas the recirculation dampers l8 will be open and the radiator valve 42 will be open. After the steam circulation end of the system has been put into operation, the radiator 4 will warm up, but there will be no change in the position of the dampers or radiator valve until the fan 6 is started. As soon thereafter as the fan is started, the auxiliary fresh air damper I! will open. The apparatus will then be developing its full heating capacity while introducing enough outdoor air to freshen the room. As a result, assuming the apparatus is of the proper size, the room temperature will soon be brought up to '70 degrees.

As the room temperature reaches 70 degrees the radiator valve 42 will begin to close and restrict the steam supply to the radiator 4, thus reducing the heating capacity of the apparatus and the rate of rise in the room temperature; and this action will progressively increase as the room temperature approaches 72 degrees. If and when a point is reached, due to this throttling action, when the room temperature ceases to rise, the control system will come to rest until there is a change of load. If, for any reason, the room temperature should then start to drop, the thermostat 29 will respond and cause the radiator valve to open enough to bring the system to rest at a slightly lower point, or, should it again begin to rise, the thermostat will respond and cause the radiator valve to close enough to bring the system to rest at a slightly higher point, provided the rise can be arrested before it reaches 72 degrees at which point the radiator valve will be fully closed. If and when the room temperature reaches 72 degrees and the steam supply is cut off, the radiator 4 will quickly cool, causing the thermostat 38 or 38a to close the auxiliary fresh air damper I1. As soon as this happens, the temperature of the air delivered by the unit ventilator will rise, due to cutting off the fresh air admixture. Consequently, the room temperature will quickly rise to adegree that will cause the thermostat 29 to open the main fresh air damper I6 enough to admit as much fresh air as had previously been admitted through the auxiliary fresh air inlet, and to correspondingly close the recirculation dampers I8. Assuming the dampers I1 and I8 are adjusted to provide a minimum fresh air suply of 33 /3%, the room temperature would rise to about 72.7 degrees in order to open the damper I6 one-third. Should the room temperature then continue to rise,. the room thermostat 29 will cause the main fresh air damper I 6 to open further and the recirculation dampers I8 to close further, thus increasing the relative proportion of fresh air until the room temperature rise is halted, when the control system will come to rest. Should the room temperature later start to drop, the thermostat 29 will respondto reverse the control action enough to bring the system to rest at a lower point. Should it begin to rise again, the thermostat will respond to further open the damper I6 and close the dampers I8 until the system is brought to rest at a slightly higher room temperature, or, until the damper I6 is wide open and the dampers I8 fully closed. In the latter event, the dampers will remain respectively fully opened and fully closed until the room temperature again falls below 74 degrees.

Referring again to the radiator 4 it will be seen that the section 4-a is positioned wholly within the air passage from the fresh air compartment 9 to the fan compartment 5, whereas the section 4-1) is positioned Wholly within the air passage from the recirculated air compartment Hi to the fan compartment. ing through the valve 42, enters a yoke fitting 44, Figure 2, which distributes the steam to the steam manifolds 45a and 45b. But, whereas the steam may fiow freely into the steam manifold 45-a through a full sized opening 46-1; it can only enter the manifold 45-h through a restricted orifice 46-12. After the steam enters the manifold 45-a it fiows freely through the tubes 4Ia into the manifold 48a from whence the condensate (and any air) drains off through a return line 49-11. After the steam enters the manifold 45b it flows into'distributing tubes 50, from whence it flows through distributing ports into encasing tubes 41-h, while the condensate (and any air) flows from said tubes into the manifold 48--b from whence it drains off through a return line 49-12. Fins 52--a may be used to help transfer the heat from the tubes 4'Ia to the air flowing between them, while fins 52-!) may serve in a like capacity for the tubes 41-13. To facilitate drainage the radiators should be pitched slightly toward the return end. If desired, the return line 49a may be connected into the return line 49b by interposing a trap (not shown). If a water sealed trap is used, it should be deep enough to Offset the difference in pressure between the manifolds 48-=-a and 48-17.

The character of service imposed on the two sections of the radiator 4 difiers. From the description of the control itis evident that the The steam supply, after passapparatus is designed to operate in two phases, a heating phase and a cooling phase, but that when it is operating in the heating phase a limited amount of fresh air is introduced for ventilation, 1. e.', to remove excess moisture and odors. The radiator 4 functions only when the apparatus is in the heating phase; but, Whereas the section 4-!) serves only to this end, by adding more or less heat to the air recirculated within the room, section la primarily serves to preheat or temper the fresh air introduced for ventilation.

Since section I-a primarily serves in a preheating capacity and is ordinarily much smaller than section 4-12, the former has a relatively small effect on the room heating capacity of the ventilator, hence, graduation of the heat output of section 4a is not necessary,but it is important that the tubes be kept filled with steam so long as heating is demanded in order to prevent cold air from entering the fan compartment and to mitigate the danger of freezing. Free flow of steam into the tubes of section 4--a is, therefore, desirable and restriction of the steam supply to the manifold -b builds up a resistance which assures that little or no steam will enter the section 4b until the demand in section 4a is fully satisfied.

On the other hand, the service of the section put; and since only recirculated air passes through this section, it is not necessary that it be kept filled with steam. However, good distribution of the steam is desirable in order to secure a good mixture of air in the fan compartment 5. The restricted ports 5| serve to hold back or choke the flow of steam in the manifold 45-!) and the inner tubes 50 so as to distribute the steam uniformly among and along the length of the tubes 4'Ib.

A pronounced advantage of the arrangement shown and described herein is that all areas of each radiator section are subject to substantially the same load, which minimizes the danger of air-binding. Heretofore in-this type of apparatus, where a mixture of fresh and recirculated air was passed through the radiator, it has been found impracticable to obtain a homogeneous mixture; and, due to temperature variation in the air stream, the duty imposed on some tubes was greater than on others. Consequently, the tubes with the lighter duty passed steam into the return manifold, which backed up in the more heavily loaded tubes and created air pockets. These air pockets within the radiator tubesproduced cold areas which not only served to lower the efliciency of the radiator but permitted streaks of cold air to pass into the room and cause drafts.

A further advantage of the present arrangement resides in the fact that the air entering the radiator section 4--b, which is mainly relied upon for graduated control action, is always of substantially the same temperature. For this reason, the control is much more reliable.

It is, of. course, to be understood that although I have described in detail a preferred embodiment of my invention, the invention is not to be thus limited, but only insofar as defined by the scope and spirit of the appended claims.

I claim as my invention:

1. In apparatus of the character described having a fresh air inlet a recirculated air inlet; and a space for mixing air from the two sources; the

combination of a steam radiator in the path of the air flowing from said inlets to said mixing space, said radiator being divided into two sections, with respect to the steam passages therethrough, means for directing all of the air from one of said inlets through one of said sections and all of the air from the other of said inlets through the other of said sections, a common source of steam supply to said sections, and means for restricting the steam flow relative to one of said sections so as to favor steam flow to the other of said sections.

2. In combination with apparatus of the character described having two damper controlled inlets for the admission of fresh air and means for thermally conditioning air admitted through one of said inlets; thermostatic means for controlling one of said dampers in response to the temperature of said thermal air conditioning means to effect the opening of said one damper when said thermal air conditioning means is operating, and thermostatic means for controlling the other of saiddampers in response to air conditions.

3. Air conditioning apparatus comprising a casing, air temperature conditioning means vertically separatiing the casing into upper and lower compartments, a partition separating the latter i compartment into chambers respectively containing a portion of the air conditioning means, a first fresh air inlet to the upper compartment, a second fresh air inlet to one of said chambers, a recirculated air inlet to the other of said chambers, interconnected dampers arranged to conversely control air flow through the first inlet, and between said other chamber and the upper compartment, thermal responsive means for controlling said interconnected dampers in accordance with the temperature of air exteriorly of said casing to open said second inlet and close said recirculated air inlet when said air temperature is high and to close said second inlet and open said recirculated air inlet when said air temperature is low, a damper arranged to control air flow through said second inlet, means responsive to the temperature of the air conditioning means for closing said last mentioned damper when said temperature is low and for opening said damper when said temperature is high, and means for collecting and discharging air from said upper compartment.

4. Apparatus for thermally conditioning air, comprising a housing enclosing a fancompartment, a fresh air compartment and a recirculated air compartment, a bafile separating said two air compartments to completely prevent air taken into said compartments from mixing until such air reaches said fan compartment, heating elements in said two air compartments on either side of saidbaiile between said air compartments and said fan compartment, a damper controlling the intake of fresh air into said fresh air compartment, a damper controlling the intake of recirculated air from said recirculated air compartment into said fan compartment, there being a second fresh air intake opening directly into said fan compartment, a damper for said second fresh air intake interconnected to said recirculated air damper, a fan in said fan compartment, means biased to hold said fresh air compartment damper closed but responsive when said fan is operating to an elevated temperature in said heating elements to open said fresh air compartment damp-= er, and means responsive to temperature conditions in a space served by said apparatus to actuate said interconnected dampers, opening-said second fresh air damper and closing the interconnected recirculated air damper when the temperature in said space is above a predetermined level and closing said second fresh air damper and opening said recirculated air damper when the temperature in said space is below said predetermined level.

5. Apparatus for delivering thermally conditioned air to an enclosed space, comprising a housing enclosing a fan compartment and having separated fresh air and recirculated air intakes remote from said fan compartment and a second fresh-air intake opening directly into said fan compartment, means for heating air from said separated fresh and recirculated air intakes before such air mixes in said fan compartment, a fan in said fan compartment, a damper for said remote fresh air intake, interconnected dampers for controlling the flow of air through said second fresh air intake and through said recirculated air intake into said fan compartment, means biased to hold said remote fresh air intake damper closed but responsive when said fan is operating to an elevated temperautre in said heating means to open said damper, and means responsive to temperatures in said enclosed space to open said fresh air intake damper and close said recirculated air damper when the temperature of said space is above a predetermined level and to close said fresh air damper and open said recirculated air damper when the temperature of said space is below such level.

6. Apparatus for delivering thermally conditioned air to a space, comprising a housing, a fan therein, heating means therein, means on the remote side of said heating means from said fan for defining separate passages for the delivery of fresh air and recirculated air past said heating means to said fan, a damper for controlling the delivery or fresh air through said fresh air passage, means responsive to the temperature of said heating means for operating said damper biased to close the same when said heating means is inoperative and energized to open the same when said fan and said heating means are both operating, an intake for fresh air directly to said fan, operatively interconnected dampers controlling said intake and said recirculated air passage and means responsive to the temperature of said space to open said fresh air intake and close said recirculated air passage when the temperature of said space is above a predetermined level and to close said fresh air intake and open said recirculated air passage when the temperature of saidspace is below said predetermined level.

'7. In apparatus for the delivery of thermally conditioned air to a space, a fan housing having two fresh air intakes and a recirculated air intake, heating means for heating fresh air passing through one of said fresh air intakes and through said recirculated air intake, operatively interconnected dampers for the other of said fresh air intakes and for said recirculated air intake, means responsive to the temperature in the space for controlling said interconnected dampers and means responsive to the temperature of said heating means for controlling the flow of air through said one fresh air intake.

8. In apparatus for the delivery of thermally conditioned air to a space, a fan housing havin two fresh air intakes and a recirculated air intake, heating means for heating fresh air passing through one of said fresh air intakes and through said recirculated air intake, operatively interconnected dampers for the other of said fresh air intakes and for said recirculated air intake, means responsive to the temperature in the space for controlling said interconnected dampers and other temperature responsive means disposed for response to temperature changes in said fresh air heating means for controlling the flow of air through said one fresh air intake.

9. In apparatus for the delivery of thermally conditioned air to a space, a fan housing having two fresh air intakes and a recirculated air intake, heating means for heating fresh air passing through one of said fresh air intakes and through said recirculated air intake, operatively interconnected dampers for the other of said fresh air intakes and for said recirculated air intake, means responsive" to the temperature in the space for controlling said interconnected dampers. means responsive to the temperature of said heating means for controlling the flow of air through said one fresh air intake, a fan in said housing for drawing air through said intakes, and an electric circuit for driving said fan and for rendering operative said last mentioned temperature responsive means.

10. Apparatus for the thermal conditioning of air for delivery to a space, comprising a fan housing having two fresh air intakes and a recirculated air intake, means for heating air passing through one only of said fresh air intakes and through said recirculated air intake, dampers for controlling the flow of air through said intakes, the dampers controlling said one fresh air intake and said recirculated air intake being operatively interconnected, and means responsive to the temperature of said space for controlling said interconnected dampers to progressively open said fresh air intake damper and close said recirculated damper when the temperature of said space is above a predetermined inlet and open said recirculated air inlet when said air temperature is low, a damper arranged to control air flow through said second inlet, means responsive to the temperature of said air conditioning means for closing said last mentioned damper when said temperature is low and for opening said damper when said temperature is high, and means for collecting and discharging air from the upper compartment.

12. Air conditioning apparatus comprising a casing, air temperature conditioning means vertically separating the casing into upper and lower compartments, a partition separating the latter compartment into chambers respectively containing a portion of the air conditioning means, a first fresh air inlet to the upper compartment.

' a second fresh air inlet to one of said chambers,

level and to reverse the operation of said dampers when the temperature of said space is below the predetermined level.

11. Air conditioning apparatus comprising a casing, air temperature conditioning means vertically separating the casing into upper and lower compartments, a partition separating the latter compartment into chambers respectively containing a portion of the air conditioning means, a first fresh air inlet to the upper compartment, a second fresh air inlet to one of said chambers, a recirculated air inlet to the other of said chambers, interconnected dampers arranged to conversely c ntrol air flow through the first inlet, and between said other chamber and the upper compartment, thermal responsive means for simultaneously controlling said interconnected dampers and said air conditioning means in accordance with the temperature of air exteriorly of said casing to open said first inlet and close said recirculated air inlet when said air temperature is high and to close said first a recirculated air inlet to the other of said chambers, interconnected dampers arranged to conversely control air flow through the first inlet. and between said other chamber and the upper compartment, air impeller means for collecting and discharging air from said upper compartment, thermal responsive means for controlling said interconnected dampers in accordance with air temperature exteriorly of said casing to open said first inlet and close said recirculated air inlet when said air temperature is high and to close said first inlet and to open said recirculated air inlet when said air temperature is low, a damper arranged to control said air flow through said second inlet, means responsive to the temperature of the air conditioning means and subject to the operation or non-operation of said impeller means for closing said last mentioned damper when said temperature is low and for opening said damper when said temperature is high.

13. In a device for thermally conditioning a room, a housing having an air inlet and an air outlet communicating with said room, an air inlet communicating with an outside source of cold air, a heating element within said housing between said inlets and said outlet, a partition on the inlet side of said heating element and serving to separate the streams of air from the two inlets until they have entered the heating element, a damper for regulating the flow of air through the cold air inlet, thermostatic r ans responsive to changes in the temperature of said heating element and being constructed and arranged to close the cold air damper when the temperature of said heating element in the vicinity of the thermostat drops below a certain point, and a damper for regulating the flow of air through said air inlet communicating with the room, and thermostatic means for indepencL ently regulating said last named damper in response to temperature changes insaid room.

GERALD E. OTIS. 

